1. Field of the Invention
The present invention relates to a pressure distribution detecting device, and, more specifically, to a pressure distribution detecting device in which a plurality of piezo-electric sensor elements are arranged in a matrix to detect distribution of contact pressure.
2. Description of the Background Art
FIG. 7 shows a piezo-electric type of pressure distribution sensor in which piezo-electric elements are arranged in a matrix for detecting distribution of contact pressure such sensor is disclosed in Japanese Patent Laying Open No. 62-297735. Referring to FIG. 7, a plurality of piezo-electric elements are arranged in a matrix of 5 rows and 5 columns. Each of connection lines A.sub.1 through A.sub.5 disposed in each row is electically connected to upper electrodes 101 of the respective piezo-electric elements 1 in each row, and each of connection lines B.sub.1 through B.sub.5 disposed in each column is electrically connected to lower electrodes 102 in each column. If a pressure in a certain piezo-electric element 1a, for example, is to be measured in this piezo-electric type of pressure distribution sensor, a potential is measured through the connection lines A.sub.1 and B.sub.1 based on a distortion caused in the piezo-electric element 1a. Then, by sequentially changing combinations of connection lines, a potential generated in each piezo-electric element is measured to obtain a pressure distribution.
A piezo-electric element generates an electric charge immediately when external force is applied thereto. Therefore, once it produces an electric charge, a potential difference between electrodes is not generated unless pressure applied to the piezo-electric element changes. Accordingly, a conventional piezo-electric type of pressure distribution sensor can obtain a pressure distribution only at a single point in time through a single measurement, so that a sequential change of pressure distributions with time cannot be obtained.